1. Field of the Invention
This invention relates generally to electronic devices having electronic circuit elements formed therein, and more particularly to an electronic device with a cooling element disposed for cooling the circuit elements.
2. Description of the Prior Art
In electronic apparatus having a large number of electronic circuit elements, e.g., computers, numerous printed circuit boards assembled with many electronic devices thereon are constructed therein. Electronic devices assembled on the printed circuit boards usually are air cooled using a blower to eliminate the heat generated during the operation of electronic devices. If the density of the generating heat on the plane of the printed circuit board is uniform, effective cooling will be accomplished using an air flow having a predetermined velocity.
However, recently, the temperature variation between electronic devices assembled on the same printed circuit board has increased with increases in the integration of logic elements and the assembly density of electronic components. In this case, the system needs a larger air flow supply to suppress the temperatures of the electronic devices below a predetermined maximum temperature. This need for a larger air flow in the conventional cooling method causes problems. Over cooling of smaller components, which generate little heat occurs, and the cooling efficiency of the device becomes worse. The loss of air flow is greater in proportion to the increased complexity of the printed circuit boards. Thus, an operator has to supply a larger air flow than is necessary, and a larger blower system is required. This causes additional problems, such as increased noise, and the like.
To overcome these problems, other conventional constructions having lower thermal resistance have been utilized, and cooling fins have been fixed on the electronic devices. However, such fins could not be enlarged sufficiently, because of space limitations resulting from the high density construction of the electronic devices.
Another conventional cooling system is shown in Japanese Patent Publication SHO 60-11840. In this system, air flows are selectively supplied to aligned electronic devices generating the higher temperatures by separating the air flows using flat plates. However, this system also needs a large blower. Moreover, freedom of design for the parts alignment on the printed circuit board becomes limited, because electronic devices generating the higher temperatures must be aligned with the air flows.